Coating composition to obtain surface effects

ABSTRACT

This invention provides a coating composition providing a soft-feel effect and enhanced suntan cream resistance, the composition comprising
         A) 5 to 50 wt %, preferably 20 to 40 wt %, of an dispersion and/or solution of at least one hydroxyl functional polyurethane, the dispersion and/or solution having a solids content in a range of 25 to 90 wt %, the wt % being based on the weight of the dispersion and/or solution,   B) 0 to 35 wt %, preferably 5 to 20 wt %, of at least one polyisocyanate as cross-linking agent,   C) 0.1 to 20 wt %, preferably 4 to 15 wt %, of at least one aqueous hydroxyl functional crosslinked (meth) acrylic latex,   D) 0 to 20 wt %, preferably 4 to 15 wt %, of organic solvent, and   E) 0.1 to 10 wt %, preferably 4 to 10 wt %, of at least one pigment, extender and/or coating additive,   the wt % being based on the total weight of the composition of A) to E).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 61/291,122 filed on Dec. 30, 2009 which is hereby incorporated byreference.

FIELD OF THE INVENTION

The invention relates to a coating composition providing a soft-feeleffect and enhanced resistance to suntan creams or lotions of the coatedsubstrates.

BACKGROUND OF THE INVENTION

To improve the haptic quality (touch feeling) of coated surfaces it isknown to use so-called soft-feel coatings particularly when used onplastic parts of automotive bodies and industrial applications. Whensoft-feel coatings are applied to interior surfaces of, for example,plastic or wooden parts, such as instrument panels, airbag covers, armrests or interior door panels, they provide a soft or leather-like feelto the surfaces of these substrates. Soft-feel coatings are particularlybased on solvent-borne and/or water-borne coating compositions based onparticularly polyurethane resins, see, for example, EP-A 1481998.

One of the disadvantages of these coatings is that they do not possessgood suntan cream resistance. Suntan cream can penetrate through thecoatings and cause delamination of the coating from the substrate.

U.S. Pat. No. 5,880,215 discloses a paint formulation based onpolyurethane dispersions in combination with polyester basedpolyisocyanates as component to improve the suntan cream resistance. InU.S. Pat. No. 6,927,254 the use of polycarbonate polyol basedpolyurethane is proposed to further improve the suntan lotionresistance.

The proposed coating compositions as known in the art and/or existing onthe market may have a crosslinking density which is not high enough toensure a sufficient suntan cream and solvent resistance. Furthermore,the goal to reduce the dry-film thickness of the coatings, due toecological effects, cannot be achieved without losing desired coatingproperties.

Therefore, there is a need to provide improved coating compositions,which have sufficiently improved resistance to suntan lotion to pass therequirements of automotive manufacturers.

SUMMARY OF THE INVENTION

This invention provides a coating composition providing a soft-feeleffect and enhanced suntan cream resistance, the composition comprising

-   -   A) 5 to 50 wt %, preferably 20 to 40 wt %, of a dispersion        and/or solution of at least one hydroxyl functional        polyurethane, the dispersion and/or solution having a solids        content in a range of 25 to 90 wt %, the wt % being based on the        weight of the dispersion and/or solution,    -   B) 0 to 35 wt %, preferably 5 to 20 wt %, of at least one        polyisocyanate as crosslinking agent,    -   C) 0.1 to 20 wt %, preferably 4 to 15 wt %, of at least one        aqueous hydroxyl functional crosslinked (meth) acrylic latex,    -   D) 0 to 20 wt %, preferably 4 to 15 wt %, of organic solvent,        and    -   E) 0.1 to 10 wt %, preferably 4 to 10 wt %, of at least one        pigment, extender and/or coating additive,    -   the wt % being based on the total weight of the composition        of A) to E).

The coating composition according to the invention provides coatingswith significantly improved resistance to suntan creams or lotionswithout losing the good soft-feel effect of the coatings. The coatingcomposition according to the invention makes it possible to reduce thedry-film thickness by keeping the above mentioned effects as well asfurther effects such as high solvent and abrasion resistance.

DETAILED DESCRIPTION OF THE INVENTION

The features and advantages of the present invention will be morereadily understood, by those of ordinary skill in the art, from readingthe following detailed description. It is to be appreciated that thosecertain features of the invention which are, for clarity, describedabove and below in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention that are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany sub-combination. In addition, references in the singular may alsoinclude the plural (for example, “a” and “an” may refer to one, or oneor more) unless the context specifically states otherwise.

Slight variations above and below the stated ranges can be used toachieve substantially the same results as values within the ranges.Also, the disclosure of these ranges is intended as a continuous rangeincluding every value between the minimum and maximum values.

The coating composition of this invention comprises as component A) adispersion and/or solution of at least one hydroxyl functionalpolyurethane, in a range of 5 to 50 wt %, preferably 20 to 40 wt %, morepreferably 20 to 36 wt %, the wt % based on the total weight of thecomposition of A) to E).

The dispersion and/or solution of the at least one hydroxyl functionalpolyurethane used in the invention may be produced, for example, bydispersing or dissolving or mixing the at least one polyurethane with asolvent and/or water, particularly deionized water, for example, bythorough dispersion of the optionally neutralized polyurethane withwater. The aqueous phase optionally containing neutralizing agent mayalso initially be introduced and the polyurethane incorporated bystirring. Continuous processing is also possible, i.e., polyurethane,water and neutralizing agent can be simultaneously homogeneously mixedin known units, such as, for example, a rotor/stator mixer as known inthe art. Conversion into the aqueous phase may also be promoted by usingan elevated temperature, for example, in a range of 40 to 90° C.

The at least one hydroxyl functional polyurethane may be prepared, forexample, by reacting linear or branched polyol components, for examplediols, with one or more organic polyisocyanates, preferablydiisocyanates, using known prior art methods.

The polyols comprise polyols familiar to the person skilled in the art,wherein proportions of polyols having a functionality of three or moremay be added in order to achieve branching of the polymer. Suitablepolyols are, for example, low molecular weight polyols, e.g., diols,triols, polyols, such as ethylene glycol, propandiol, 1,6-hexandiol,1,2-cyclohexandiol, bisphenol A and mixtures thereof. Also diols derivedfrom fatty alcohols can be used. Additional examples of polyols may bepolyether polyols and polyester polyols. The polyether polyols may, forexample, exhibit a general formula of HO—(CHR⁴)_(n)—_(m)OH, in which R⁴is hydrogen, C1 to C6 alkyl, optionally with various substituents, n=2to 6 and m=10 to 50 or more, wherein the residues R⁴ may be identical ordifferent. Polyester polyols may, for example, be produced byesterifying organic dicarboxylic acids or the anhydrides thereof withorganic polyols. The dicarboxylic acids and polyols may be aliphatic,cycloaliphatic or aromatic dicarboxylic acids and polyols. Thedicarboxylic acids may be long-chain dicarboxylic acids having 18 to 60chain carbon atoms. The polyester polyols preferably have a numberaverage molecular weight of 300 to 6000, an OH value of 20 to 400 and anacid value of <3, preferably of <1. Polycarbonate diols may also be usedas polyols, also polyols derived from lactones. These products areobtained, for example, by reacting an epsilon-caprolactone with a diol,wherein these polylactone polyols are distinguished by the presence of aterminal hydroxyl group and by repeat polyester moieties derived fromthe lactone. The lactone may be any desired lactone or any desiredcombination of different lactones, for example, having 6 to 8 ringcarbon atoms.

Additional compounds that are usable as polyol components are, forexample, OH- and/or SH-containing polythioethers, OH-containingpolyacetals, polyether-esters, OH-containing polyester-amides andpolyamides, dihydroxypolyester carbonates, polyurethane diols,poly(meth)acrylate polyols, polybutanediene oil diols andhydroxy-functionalized siloxane copolymers. Linear polyester polyols andpolyether polyols are preferably used.

As organic polyisocyanates, any aliphatic, cycloaliphatic or aromatic aswell as sterically hindered isocyanates, which may for example alsocontain ether or ester groups, may be used, for example, diisocyanates.Polyisocyanates showing a higher isocyanate functionality than thosedescribed before, may also be used, e.g., polymeric polyisocyanates.Preferred isocyanates are those containing approximately 3 toapproximately 36, particularly, approximately 8 to 15 carbon atoms.Examples of suitable diisocyanates are: hexamethylene diisocyanate,toluoylene diisocyanate, isophorone diisocyanate, hexane diisocyanate.Oligomeric diisocyanates are preferred.

Examples of hydroxyl functional polyurethanes are BAYHYDROL®LS 2244 andBAYHYDROL® LS 2305 of Bayer.

The hydroxyl functional polyurethanes are those, for example, with anumber average molecular mass Mn of 1000 to 500 000 g/mol, preferably5000 to 300 000 g/mol, an acid value of 10 to 100 mg KOH/g, preferablyof 20 to 80 mg KOH/g, and a hydroxyl value of 0 to 400 mg KOH/g.

The term number average molar mass Mn stated in the present descriptionmeans the number average molar mass determined or to be determined bygel permeation chromatography (GPC) with divinylbenzene crosslinkedpolystyrene as the immobile phase, tetrahydrofuran as the liquid phaseand polystyrene standards, as defined in ISO 13885-1.

The various types of hydroxyl functional polyurethanes may be used aloneor as a mixture of two or more thereof.

The term (meth) acryl is respectively intended to mean acryl and/ormethacryl.

If the hydroxyl functional polyurethanes according to the inventioncontain groups that are capable of forming ions, said groups areentirely or in part converted into the corresponding salts using asuitable compound, for example, a neutralizing agent, as known at aperson skilled in the art, wherein care must be taken to ensure that thecompounds used for salt formation are selected such that they arechemically inert during synthesis. Ion-forming groups that may bepresent are those capable of forming anions or cations, as known by aperson skilled in the art. Preferred are those groups capable of forminganions. In this case, a base, as known at a person skilled in the art,for example, NaOH, KOH, LiOH, ammonia, primary, secondary and tertiaryamines such as diethylamine, triethylamine, morpholine; alkanolaminessuch as diisopropanolamine, dimethylaminoethanol, triisopropanolamine,dimethylamino-2-methylpropanol; quaternary ammonium hydroxides or alsomixtures of such neutralising agents can be used for conversion intoanions.

The hydroxyl functional polyurethanes usable according to the inventionmay be solvent-free or may be used dissolved or mixed in a solvent.Solvents that may be used are water-miscible solvents orwater-immiscible solvents. Examples of suitable solvents are mono- orpolyhydric alcohols, glycol ethers or esters, glycols, ketones, aromaticor aliphatic hydrocarbons, alkylpyrrolidones, ethers, and cyclic ureaderivatives.

The solvent-free or solvent-containing hydroxyl functional polyurethaneaccording to the invention may be converted into the aqueous phase byaddition of sufficient quantities of water, particularly deionizedwater. A finely divided polyurethane dispersion and/or solution can thenbe obtained having an average particle size of, for example, >10 and<2000 nm, preferably in a range of 50 to 500 nm. The solids content ofthe dispersion and/or solution of the at least one hydroxyl functionalpolyurethanes is between 25 and 90 wt %, preferably above 35 to 60 wt %,based on the dispersion and/or solution of the at least one hydroxylfunctional polyurethane.

The term average particle size mentioned in this document isrespectively intended to mean the D90 value. The D90 value correspondsto a particle size below which 90 weight % of the particles lie, whereinthe particle size analysis is done by PCS (Photon CorrelationSpectroscopy) and meets the standards set forth in ISO 13321.Measurement is done on a Malvern Zetasizer 4000.

It is not generally necessary to use emulsifiers to convert the hydroxylfunctional polyurethane into aqueous dispersions, but emulsifiers maynevertheless be used, in amounts known in the art. Examples ofemulsifiers are ionic or nonionic emulsifiers that facilitateemulsification and optionally, reduce the number of ionizable groups.

Solvents optionally present in the polyurethane dispersion and/orsolution according to the invention may, if desired, be removed bydistillation, for example under reduced pressure.

The polyurethane dispersion and/or solution according to the inventionmay be self-crosslinked, physically dried or externally crosslinked bymethods known in the art.

In case of self-crosslinkable polyurethane dispersion and/or solutionthe polyurethane contains crosslinkable functional groups known by aperson skilled in the art. In this case, no crosslinking agent needs tobe used in the composition according to the invention.

The coating composition according to the invention may contain at leastone crosslinking agent as component B) for external crosslinking, in arange of 0 to 35 wt %, preferably 5 to 20 wt %, more preferably 5 to 17wt %, the wt % based on the total weight of the composition of A) to E).

Various polyisocyanates, blocked or unblocked, may be used ascrosslinking agents. Blocked polyisocyanates may be any desiredpolyisocyanates in which the isocyanate groups have been reacted withblocking agent(s) known in the art in such a manner that the resultantblocked polyisocyanate is resistant to hydroxyl groups and water at roomtemperature, but reacts at elevated temperatures, for example, in therange of 90 to 250° C. It is also possible to use unblockedpolyisocyanates. Aliphatic, cycloaliphatic or aromatic as well assterically hindered isocyanates may be used, as may alsopolyisocyanates, for example, diisocyanates, comprising ether or estergroups. Preferred isocyanates are those which contain approximately 3 toapproximately 36, in particular, approximately 8 to 15 carbon atoms.Examples of suitable diisocyanates are hexamethylene diisocyanate,tolylene diisocyanate, isophorone diisocyanate, hexane diisocyanate.Oligomeric diisocyanates are preferred. Polyisocyanates of greaterisocyanate functionality than those described above, as known in theart, for example, polymeric polyisocyanates, may also be used. Thecrosslinking agents may be used individually or as a mixture.

The coating composition according to the invention comprises at leastone aqueous hydroxyl functional crosslinked (meth) acrylic latex ascomponent C) in a range of 0.1 to 20 wt %, preferably 4 to 15 wt %, morepreferably 4 to 12 wt %, the wt % based on the total weight of thecomposition of A) to E).

The term aqueous hydroxyl functional crosslinked (meth)acrylic latex isrespectively intended to mean water-dispersed (meth)acrylic emulsionpolymer, i.e. water-dispersed polymer particles prepared by emulsionpolymerizing free-radically polymerizable olefinically unsaturated(meth)acrylic monomers optionally in combination with otherfree-radically polymerizable olefinically unsaturated monomers.

The at least one aqueous hydroxyl functional crosslinked (meth) acryliclatex can be prepared by multistage emulsion polymerization in theaqueous phase, comprising the steps:

-   -   1) free-radical polymerization of a mixture A1 of olefinically        unsaturated, free-radically polymerizable monomers, optionally        comprising at least one monomer with at least one acid group and        at least one olefinically polyunsaturated monomer, in the        aqueous phase,    -   2) free-radical polymerization of at least one mixture B1 of        olefinically unsaturated, free-radically polymerizable monomers,        optionally comprising at least one monomer with at least one        acid group and at least one olefinically polyunsaturated monomer        in the presence of the product obtained in process step 1),        wherein the ratio by weight of mixture A1 to the at least one        mixture B1 is from 15:85 to 85:15 and wherein mixture A1 or the        at least one mixture B1 or both mixture A1 and the at least one        mixture B1 comprise the at least one monomer with at least one        acid group and wherein mixture A1 or the at least one mixture B1        or both mixture A1 and the at least one mixture B1 comprise the        at least one olefinically polyunsaturated monomer.

Preferably, mixture A1 comprises at least one monomer with at least oneacid group in a proportion corresponding to an acid value of mixture Aof 10 to 100 mg of KOH/g and 0.5 to 5 wt % of at least one olefinicallypolyunsaturated monomer.

Preferably, mixture B1 comprises at least one monomer with at least oneacid group in a proportion corresponding to an acid value of mixture B1of 0 to below 5 mg of KOH/g, at least one monomer with at least onehydroxyl group in a proportion corresponding to a hydroxyl value ofmixture B1 of 0 to below 5 mg of KOH/g and at least one olefinicallypolyunsaturated monomer in a proportion of 0.5 to 5 wt. %, relative tomixture B1.

The aqueous hydroxyl functional crosslinked (meth) acrylic latex isproduced by a multistage, preferably two-stage emulsion polymerization,i.e. the mixtures A1 and B1 of olefinically unsaturated monomers to befree-radically polymerized are polymerized under conventional conditionsknown to the person skilled in the art of a free-radical polymerizationperformed in an aqueous emulsion, i.e. using one or more emulsifiers andwith the addition of one or more initiators which are thermallydissociable into free radicals. In order to ensure the formation of acrosslinked or even gel structure in the polymer products formed in atleast one of the stages of the emulsion polymerization, olefinicallypolyunsaturated monomers are used and copolymerized.

Examples of olefinically unsaturated, free-radically polymerizablemonomers with at least one acid group are in particular olefinicallyunsaturated monomers containing carboxyl groups, such as, for example,(meth)acrylic, itaconic, crotonic, isocrotonic, aconitic, maleic andfumaric acid, semi-esters of maleic and fumaric acid and carboxyalkylesters of (meth)acrylic acid, for example, beta-carboxyethyl acrylateand adducts of hydroxyalkyl(meth)acrylates with carboxylic anhydrides,such as, for example, phthalic acid mono-2-(meth)acryloyloxyethyl ester.(Meth)acrylic acid is preferred.

Examples of olefinically polyunsaturated, free-radically polymerizablemonomers are divinylbenzene, hexanediol di(meth)acrylate, ethylene andpropylene glycol di(meth)acrylate, 1,3- and 1,4-butanedioldi(meth)acrylate, vinyl(meth)acrylate, allyl(meth)acrylate, diallylphthalate, glycerol tri(meth)acrylate, trimethylolpropanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate, di- andtripropylene glycol di(meth)acrylate, hexamethylene bis(meth)acrylamide.Further examples are compounds which may be produced by a condensationor preferably by an addition reaction of complementary compounds, whichin each case, in addition to one or more olefinic double bonds, containone or more further functional groups per molecule. The furtherfunctional groups of the individual complementary compounds comprisepairs of mutually complementary reactive groups, in particular groupswhich are capable of reacting with one another for the purposes of apossible condensation or addition reaction.

Examples of olefinically polyunsaturated, free-radically polymerizablemonomers produced by a condensation reaction are reaction productsformed from alkoxysilane-functional (meth)acrylic monomers afterhydrolysis with elimination of alcohol and formation of siloxanebridges. Further examples are reaction products formed fromhydroxyalkyl(meth)acrylates and olefinically unsaturated isocyanatesblocked on the isocyanate group, such as isocyanatoalkyl(meth)acrylateor m-isopropenyl-alpha,alpha-dimethylbenzyl isocyanate with eliminationof the blocking agent and formation of urethane groups.

Examples of olefinically polyunsaturated, free-radically polymerizablemonomers produced by an addition reaction are addition products formedfrom hydroxyalkyl(meth)acrylates and olefinically unsaturatedisocyanates, such as isocyanatoalkyl(meth)acrylate orm-isopropenyl-alpha,alpha-dimethylbenzyl isocyanate with formation of aurethane group or reaction products formed by ring-opening addition ofthe epoxy group of unsaturated epoxy compounds onto the carboxyl groupof an unsaturated acid with formation of an ester group and a hydroxylgroup, such as, for example, the addition product formed from glycidyl(meth)acrylate and (meth)acrylic acid.

Apart from the at least one olefinically unsaturated, free-radicallypolymerizable monomer with at least one acid group and the at least oneolefinically polyunsaturated, free-radically polymerizable monomer,mixture A1 and the at least one mixture B1 also comprise one or morefurther olefinically unsaturated, free-radically polymerizable monomers.These may comprise functional groups or they may be non-functionalizedand they may also be used in combination.

Examples of olefinically unsaturated, free-radically polymerizablemonomers without functional groups usable in mixture A1 are monovinylaromatic compounds such as styrene, vinyltoluene; vinyl ethers and vinylesters, such as vinyl acetate, vinyl versatate; maleic, fumaric,tetrahydrophthalic acid dialkyl esters; but in particular (cyclo)alkyl(meth)acrylates, such as methyl(meth)acrylate, ethyl(meth)acrylate,propyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate,tert.-butyl (meth)acrylate, hexyl(meth)acrylate,cyclohexyl(meth)acrylate, ethylhexyl(meth)acrylate, decyl(meth)acrylate,dodecyl(meth)acrylate, hexadecyl(meth)acrylate, lauryl(meth)acrylate andisobornyl (meth)acrylate.

Examples of olefinically unsaturated, free-radically polymerizablemonomers with functional groups which may be mentioned are in particularolefinically unsaturated monomers with at least one hydroxyl group, suchas allyl alcohol, but in particular hydroxyalkyl(meth)acrylates such as,for example, hydroxyethyl(meth)acrylate, and the hydroxypropyl(meth)acrylates, hydroxybutyl(meth)acrylates isomeric with regard to theposition of the hydroxyl group. Further examples are glycerolmono(meth)acrylate, adducts of (meth)acrylic acid onto monoepoxides,such as, for example, versatic acid glycidyl ester and adducts ofglycidyl (meth)acrylate onto monocarboxylic acids such as, for example,acetic acid or propionic acid.

The duration of the emulsion polymerization (time taken to apportionmixtures A1 and B1 into the aqueous initial charge plus the duration ofthe neutralization operation plus the duration of thepost-polymerization phase) is, for example, 1 to 10 hours. Thepolymerization temperature in the aqueous phase is, for example, 50 to95° C.

The emulsifier(s) is/are used in a conventional total quantity of, forexample, 0.1 to 3 wt %, relative to the sum of the weights of mixturesA1 and B1 and may be initially introduced and/or added as a constituentof the mixtures A1 and B1 and/or added in parallel to the addition ofmixtures A1 and B1. Examples of usable emulsifiers are the conventionalcationic, anionic and nonionic emulsifiers usable in the context ofemulsion polymerization, such as, for example, cetyltrimethylammoniumchloride, benzyldodecyldimethylammonium bromide, sodium dodecyl sulfate,sodium dodecylbenzenesulfonate, polyethylene glycol monolauryl ether.Care must be taken to ensure that cationic and anionic emulsifiers arenot used with one another.

The initiator(s) which are thermally dissociable into free radicals(free-radical initiators) are used in a conventional total quantity of,for example, 0.02 to 2 wt %, relative to the sum of the weights ofmixtures A1 and B1 and are added contemporaneously with the addition ofmixtures A1 and B1. Water-soluble free-radical initiators may be addedas such, as a constituent of mixtures A1 and B1, but in particular as anaqueous solution. A portion of the free-radical initiators may, however,be initially introduced and/or added once addition of the monomers iscomplete. The free-radical initiators are preferably water-soluble.Examples of usable free-radical initiators are hydrogen peroxide,peroxodisulfates, ammonium salts of 4,4′-azobis(4-cyanopentanoic acid),2,2′-azobis(2-methyl-N-1,1-bis(hydroxymethyl)ethyl)propionamide,2,2′-azobis(2-methyl-N-2-hydroxyethyl)propionamide as well asconventional redox initiator systems known to the person skilled in theart.

The monomer mixtures A1 and B1 according to process steps 1) and 2) areadded, as usually done in emulsion polymerizations, into an aqueousinitial charge, which has generally already been adjusted to thepolymerization temperature. Process steps 1) and 2) consequentlycomprise the addition of mixtures A1 and B1. Mixtures A1 and B1 areadded one after the other according to process steps 1) and 2), whereinthe addition of the one or more mixtures B1 is begun with process step2), but at the earliest after completion of process step 1, and in themost preferred embodiment, at the earliest once at least 90 wt % of themonomers of mixture A1 have been polymerized and the neutralizationaccording to process step 1a) has been performed. The extent to whichthe polymerization has been taken to completion may readily bedetermined by determining the solids content. The addition of the atleast one mixture B1 into the aqueous initial charge may thus begin incase of the most preferred embodiment at the earliest after thepolymerization of 90% of mixture A1 and the subsequent addition of theneutralizing agent in process step 1, which corresponds to the case of avery high rate of polymerization with virtually instantaneous 100%polymerization conversion. In general, however, mixture A1 is initiallyadded in its entirety during process step 1), after which theneutralizing agent can be added once the mixture A1 monomers have beenat least 90%, preferably completely, polymerized and only thereafter,during process step 2), is the at least one mixture B1 added.

The acid groups of the polymer obtained in process step 1) and/or inprocess step 2) are neutralized using conventional basic neutralizingagents, such as ammonia and in particular amines and/or aminoalcoholssuch as, for example, triethylamine, dimethylisopropylamine,dimethylethanolamine, dimethylisopropanolamine and2-amino-2-methyl-1-propanol.

The basic neutralizing agents are added in accordance with a degree ofneutralization of, for example, 10 to 100%. A degree of neutralizationof 100% here corresponds to a stoichiometric neutralization of each acidgroup in the polymer arising from mixture A1 and/or B1. For example, thedegree of neutralization is selected dependent on the solids content ofthe aqueous binder latex obtained after completion of the process andalso dependent on the acid value of the corresponding monomer mixture.In general, a low degree of neutralization is selected in the case ofelevated acid values and elevated solids content and vice versa.

The term “mixture” used in connection with mixtures A1 and B1 does notexclude separate addition of the particular monomers, i.e. the monomersmay also be added individually or as two or more different mixtures ofonly some of the monomers. It is preferred, however, to add separatemixtures A1 and B1. Mixtures A1 and B1 may also be added in the form ofpre-emulsions.

The ratio by weight of mixture A1 to the at least one mixture B1 is15:85 to 85:15.

The polymerization process described above permits the production ofaqueous hydroxyl functional crosslinked (meth) acrylic latices withsolids contents of, for example, 30 to 60 wt. %.

The average particles size of the can be in the range of the solids inthe aqueous hydroxyl functional crosslinked (meth) acrylic lattices canbe in the range of preferably 30 to 500 nm.

The coating composition according to the invention may comprise solventsas component D) in a range of 0 to 20 wt %, preferably 4 to 15 wt %,most preferably 4 to 12 wt %, the wt % based on the total weight of thecomposition of A) to E). Suitable solvents that may be present areconventional coating solvents, which may originate from production ofthe polyurethane or are added separately. Examples of such solvents arethose as mentioned above. The flow and viscosity of the coatingcomposition may be influenced by selection of the solvents, while theevaporation behavior of the coating composition may be influenced by theboiling point of the solvent mixture used.

The coating composition according to the invention comprises at leastone pigment, extender and/or coating additive as component E) in a rangeof 0.1 to 10 wt %, preferably 4 to 10 wt %, more preferably 4 to 8 wt %,the wt % based on the total weight of the composition of A) to E).

Examples of pigments are colour-imparting and/or specialeffect-imparting pigments. Suitable colour-imparting pigments are anyconventional coating pigments of an organic or inorganic natureconsidering their stability within the coating composition of theinvention and also regarding the withstanding of the curing conditionsof the composition of the invention. Examples of inorganic or organiccolour-imparting pigments are titanium dioxide, micronized titaniumdioxide, carbon black, iron oxide, azo pigments, and phthalocyaninepigments. Examples of special effect-imparting pigments are metalpigments, for example, made from aluminium, copper or other metals,interference pigments, such as, metal oxide coated metal pigments andcoated mica.

Examples of usable extenders are silicon dioxide, aluminium silicate,barium sulfate, calcium carbonate, magnesium carbonate and micronizeddolomite, as known in the art.

The pigments can be incorporated into the coating composition usingconventional methods. Special effect-imparting pigments can beincorporated, for example, in the form of a conventional commercialaqueous or non-aqueous paste. Colour-imparting pigments or extenders canbe incorporated, for example, with grinding in a proportion of theaqueous polyurethane, wherein grinding may also be performed in aspecial, water-dilutable paste resin.

Examples of coating additives are the common known coating additivessuch as levelling agents, rheological agents such as highly dispersedsilica or polymeric urea compounds, thickeners, defoamers, wettingagents, anticratering agents, degassing agents, thermolabile initiators,antioxidants and light stabilizers based on HALS (hindered amine lightstabilizer) products, tribo-charging agents, accelerators, initiators,inhibitors and catalysts.

Catalysts may optionally be used to accelerate curing. It is, however,also possible to cure with thermal energy without using a catalyst.

The coating composition according to the invention may also contain oneor more additional binders. This may be advantageous, for example, inorder to achieve certain synergistic effects. Examples of additionalbinders are the conventional film-forming resins familiar to the personskilled in the art, for example in a range of 0 to 20 wt %, based on thetotal weight of the composition of A) to E). Preferably, no suchadditional binders are used.

The coating composition of this invention comprising the components A)to E) may be prepared in such a manner that the components A) and C) toE) are mixed together under addition of deionized water to provide asolids content in a range of 30 to 40%, preferably 34 to 38%, based onthe components A) and C) to E). This mixture can then be combined withthe component B) in a ratio in a range of 90:10 to 70:30, based on thetotal weight of the composition.

The coating material according to the invention may be applied usingconventional methods, preferably being applied by spraying to a dry filmthickness of 8 to 500 μm, preferably 8 to 50 μm, more preferably 15 to35 μm. Application is preferably performed using the wet-on-wet processwith drying or crosslinking at temperatures, for example, of 20 to 140°C., object temperature in each case, as generally known in the art.

The applied coating composition can be dried or cured by thermal energy.The coating layer may, for example, be exposed to convective, gas and/orradiant heating, e.g., infra red (IR) and/or near infra red (NIR)irradiation, as known in the art. If the coating composition containsunsaturated resins and, optionally, photo-initiators the curing processcan be done by a polymerisation step by irradiation with high energysuch as ultra violet (UV) or electron beam (EB) radiation. If thecoating composition contains resins having thermally reactive functionstogether with resins having unsaturated functions, dual curing may beused which means a combination of curing with high energy irradiationand thermal curing, with methods described above.

The coating composition according to the invention may be used inmulti-layer coatings. The coating composition of this invention may beused as a clear coat with or without the use of transparent pigments.

The multi-layer coatings may be applied onto the substrates in variousmanners. Plastic substrates may, for example, be provided with a plasticprimer, onto which the coating composition according to the invention isapplied and cured. The coating composition according to the inventionmay also be applied wet-on-wet onto uncrosslinked filler layers and thenbe cured together with the filler layer.

It is also possible to apply the coating composition according to theinvention directly without further inter-layers, onto the substrate, asone-layer coating.

The coating composition according to the invention may also be used asan aqueous top coat in multi-layer coatings, for example, applied onto acolor-imparting base coat. Suitable base coats are in principle anyknown base coats. Not only solvent-containing one- or two-componentcoating compositions, but also water-dilutable base coats orradiation-curable base coats may be used. Such multilayer coatings maylikewise be applied onto the substrates in various manners. Plasticsubstrates may be provided with a plastic primer, onto which the basecoat layer is applied and cured. The base coat may also be appliedwet-on-wet onto uncrosslinked filler coats, then cured together with thefiller coat, generally prior to application of a clear top coat,whereupon the coating composition according to the invention may then beapplied and cured.

Suitable substrates for coating with the coating composition accordingto the invention are substrates made from metal, plastics, concrete,wood and films (plastic films, paper sheets), in particular, plasticindustrial and automotive parts, in particular, plastic parts forinteriors.

The invention furthermore relates to a substrate coated with the coatingcomposition according to the invention optionally in conjunction with amultilayer system, and drying or curing of the coating on the substrate.

The multi-layer system may be obtained by applying at least one primercoat, preferably based on a water-dilutable coating composition,applying a conventional color-imparting base coat layer, optionallydrying the base coat and applying a transparent coating compositioncomprising the coating composition according to the invention as the topcoat and subsequently heating the coated substrate. Further, additionallayers may optionally be added to this multi-layer coating. The primercoat may also be omitted.

The multi-layer coating according to the invention exhibits a goodsurface with very good interlayer adhesion. In particular, using thecoating composition according to the invention it is possible to achievea surface finish with a pleasantly soft appearance (soft-feel effect).

Substrates coated with the coating composition according to theinvention may be used for the most varied purposes. For example, it ispossible to use the process according to the invention to coatsubstrates that are used for insulation purposes, i.e. for acoustic aswell as thermal insulation. The composition according to the inventionmay furthermore be used to equip the substrates in accordance withvarious requirements with regard to acoustic properties, for example inorder to achieve certain acoustic behaviour. Finally, the processaccording to the invention may be used to provide an attractive,decorative finish on substrate surfaces and to achieve certain tactileproperties, for example, a soft appearance. The substrates coated usingthe process according to the invention are readily cleanable and arevery durable, i.e. exhibit an extended service life of the coating whileretaining the desired properties.

The following example illustrates the invention. It should be understoodthat these Examples are given by way of illustration only.

EXAMPLES Example 1 Preparation of a Coating Composition of the Invention

1.1:To 20 parts per weight of OH-functional polyurethane dispersion(BAYHYDROL® LS 2244/1) 4 parts per weight of silica dioxide, 2.5 partsper weight of wetting agent and solvent are added while stirring. Anamount of trialkylamine is added to the mixture to provide a pH value of8 to 8.2, and deionized water is added to provide the solids content of36 to 40% of the resulted aqueous mixture. The resulted mixture isdispersed until a particle size of 15 to 20 μm is received.1.2:To 66 parts per weight of the above resulted aqueous mixture 8 parts perweight of the hydroxyl functional crosslinked (meth) acrylic latex, 2 to3 parts per weight of wetting agent and pigments prepared as paste areadded. An amount of trialkylamine is added to the mixture to provide apH value of 8 to 8.2, and deionized water is added to provide the solidscontent of 34 to 38% of the resulted aqueous mixture.

Exactly before the application process, 17 wt % of a HDI-solution(hexamethylene diisocyanate solution) as curing agent (solids content:50 to 52 wt %) are added to the above prepared aqueous dispersion forhomogenization within 10 minutes at 1000 rpm.

Example 2 Coating Composition of Prior Art

To 66 parts per weight of the resulted aqueous mixture under Example 1.1a polyester urethane dispersion (BAYHYDROL® LP RSC 1187) is added in anamount of 8 parts per weight, and further 2 to 3 parts per weight ofwetting agent and pigments prepared as paste are added. The coatingcomposition is then prepared in the same way as described under Example1.2.

Example 3 Application and Tests

The application process takes place by means of 3 to 4 cross-coatspraying steps on a plastic surface with a dry-film thickness of 20 to25 μm (dry-film thickness according to DIN EN ISO 2178 for metalsurfaces and comparison with the dry-film thickness on the plasticsurface).The test results can be seen in Table 1.

TABLE 1 Adhe- Suntan Suntan sion Cream 1 Cream 2 Cross (LSF 30) (LSF 45)Abrasion Cut Soft Scratch Scratch Hydrolysis Resistance DIN Appea-Resis- Resis- 72 h at 90 (Crock- Coating EN rance tance tance +/− 2° C.meter) Compo- ISO (Haptic- DIN EN DIN EN 96% rel. DIN EN 20 sition 2409visually) ISO 1518 ISO 1518 humidity 105-A03 Example 0 O.K. O.K. O.K.Scratch 2 1 Resistance DIN EN ISO 1518: O.K. Example 0 O.K. not O.K notO.K. Scratch 1 2 Resistance DIN EN ISO 1518: O.K.

1. A coating composition comprising A) 5 to 50 wt % of an dispersionand/or solution of at least one hydroxyl functional polyurethane, thedispersion and/or solution having a solids content in a range of 25 to90 wt %, the wt % being based on the weight of the dispersion and/orsolution, B) 0 to 35 wt % of at least one polyisocyanate ascross-linking agent, C) 0.1 to 20 wt % of at least one aqueous hydroxylfunctional crosslinked (meth) acrylic latex, D) 0 to 20 wt % of organicsolvent, and E) 0.1 to 10 wt % of at least one pigment, extender and/orcoating additive, the wt % being based on the total weight of thecomposition of A) to E).
 2. The coating composition of claim 1comprising A) 20 to 40 wt % of an dispersion and/or solution of at leastone hydroxyl functional polyurethane, the dispersion and/or solutionhaving a solids content in a range of 25 to 90 wt %, the wt % beingbased on the weight of the dispersion and/or solution, B) 5 to 20 wt %of at least one polyisocyanate as cross-linking agent, C) 4 to 15 wt %of at least one aqueous hydroxyl functional crosslinked (meth) acryliclatex, D) 4 to 15 wt % of organic solvent, and E) 4 to 10 wt % of atleast one pigment, extender and/or coating additive, the wt % beingbased on the total weight of the composition of A) to E).
 3. A coatedsubstrate coated with the coating composition of claims 1 and 2.